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<title>Berkeley DB Reference Guide: Release 4.3: ENOMEM and DbMemoryException</title>
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<td><b><dl><dt>Berkeley DB Reference Guide:<dd>Upgrading Berkeley DB Applications</dl></b></td>
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<p align=center><b>Release 4.3: ENOMEM and DbMemoryException</b></p>
<p>In versions of Berkeley DB before 4.3, the error <b>ENOMEM</b> was used to
indicate that the buffer in a <a href="../../api_c/dbt_class.html">DBT</a> configured with
<a href="../../api_c/dbt_class.html#DB_DBT_USERMEM">DB_DBT_USERMEM</a> was too small to hold a key or data item being
retrieved.  The 4.3 release adds a new error, <a href="../../api_c/dbt_class.html#DB_BUFFER_SMALL">DB_BUFFER_SMALL</a>,
that is returned in this case.</p>
<p>The reason for the change is that the use of <b>ENOMEM</b> was
ambiguous: calls such as <a href="../../api_c/db_get.html">DB-&gt;get</a> or <a href="../../api_c/dbc_get.html">DBcursor-&gt;get</a> could return
<b>ENOMEM</b> either if a <a href="../../api_c/dbt_class.html">DBT</a> was too small or if some resource
was exhausted.</p>
<p>The result is that starting with the 4.3 release, C applications should
always treat <b>ENOMEM</b> as a fatal error.  Code that checked for
the <b>ENOMEM</b> return and allocated a new buffer should be changed
to check for <a href="../../api_c/dbt_class.html#DB_BUFFER_SMALL">DB_BUFFER_SMALL</a>.</p>
<p>In C++ applications configured for exceptions, a
<a href="../../api_cxx/memp_class.html">DbMemoryException</a> will continue to be thrown in both cases,
and applications should check the errno in the exception to determine
which error occurred.</p>
<p>In Java applications, a <b>DbMemoryException</b> will be thrown
when a <b>Dbt</b> is too small to hold a return value, and an
<b>OutOfMemoryError</b> will be thrown in all cases of resource
exhaustion.</p>
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